DE602004003065T2 - METHOD AND CIRCUIT ARRANGEMENT FOR SELF-TESTING A REFERENCE VOLTAGE IN ELECTRONIC COMPONENTS - Google Patents

Abstract

A method for the self-testing of a reference voltage in electronic components includes a circuit arrangement for a self-test of the reference voltage that can be implemented in the form of an on-chip test, eg., for which no external reference voltage source is required. The reference voltage (U<SUB>ref</SUB>) is fed to a voltage-controlled oscillator whose output forms the input to a Wien-Robinson bridge whose output signal is checked in a phase detector for its phase shift relative to the input to the Wien-Robinson bridge to check the balance of the Wien-Robinson bridge. The Wien-Robinson bridge is set to be balanced at a frequency (OMEGA<SUB>ref.test</SUB>) that is generated in the oscillator at the nominal value<SUB>(Uref.tes) </SUB>selected for the reference voltage (U<SUB>ref</SUB>), and a pass signal is generated if the bridge is balanced and a fail signal is generated if it is not.

Description

The The invention relates to a method and a circuit arrangement for Self-test of a reference voltage in electronic components.

integrated Circuits need be tested in the manufacturing process, but also in field operation, to ensure their correct functioning. There external test devices are associated with many disadvantages, because each chip must be contacted individually and a subsequent chip check below Operating conditions no longer possible is, have test circuits enforced, which are integrated into the chip itself. This method is known as BIST ("built-in self-test"). With the BIST turns a chip into a closed identification process offered by mistakes.

The Circuits often come with internally regulated voltage sources equipped, as reference voltage sources for comparison with voltages or streams serve within the integrated circuit associated with the circuits. These reference voltage sources are to temperature effects and external power supply means with fluctuating voltages as possible be insensitive. To allow a test to compliance checking these conditions is It is known to provide a reference voltage of such a source with a compare external reference voltage. This already has the above for the BIST described disadvantage that in field operation of the chip contacting from the outside would have to be done something extraordinary Effort would be connected.

The document US-A-5773967 discloses a voltage reference with self-monitoring properties using semiconductor switches.

The Document "Vienna-Robinson-Oscillator zur Measuring small capacity changes, "Dai Ming Yuan, in electronics, Franzis publishing house GmbH, describes the use of the Vienna-Robinson-Bridge for measurement purposes.

Of the Invention is the object of a circuit arrangement for a Self-test the reference voltage to be performed as an on-chip test can, that is, for the no external reference voltage source is needed.

According to the invention Problem solved by the features of claims 1 and 2.

After that the reference voltage is fed to a voltage-dependent oscillator whose output forms the entrance of a Wien-Robinson-Brücke, whose output signal in a phase detector with respect to its phase shift relative to the entrance of the Vienna-Robinson-Bridge is checked for the comparison of the Vienna-Robinson-Bridge. The bridge equilibrium is set to a frequency that is in the oscillator at the for the Reference voltage selected Nominal the phase shift has zero. In this case generated the phase detector a pass signal, otherwise a fail signal.

A associated Circuit arrangement has a voltage-dependent oscillator whose output voltage led to a Vienna-Robinson-Bridge, whose output forms the input of a phase detector.

The Invention is based on the accompanying drawings be explained in more detail.

It demonstrate:

1 the principle of the self-test based on a block diagram and

2 the construction of the Vienna-Robinson-Bridge.

The on-chip reference test according to the invention is based on a Wien-Robinson bridge W, which measures a frequency. In order to generate a voltage with a specific frequency from a reference voltage U _ref to be tested, a voltage-dependent oscillator O is used which generates the frequency f _x≈ to be tested from the reference voltage U _ref . The dependence of the frequency f _{x≈ of} the oscillator on the input voltage must be unique. The outputs a and b of the Wien-Robinson bridge are then compared with each other via the phase detector P.

The adjustment conditions for the Vienna-Robinson-Bridge are:

With balanced bridge, the phase of the output voltage of the bridge has a zero crossing. The values of the resistors R0, R1, R2, R3 and the capacitors C0, C1 of the Wien-Robinson bridge are therefore selected such that the phase shift at the nominal value U _{ref, test} selected for the reference _voltage U _{ref is} zero. The phase detector now checks the phase shift between the two outputs a and b of the Wien-Robinson-Brücke. Due to the result can be a statement about the correctness of the tested th reference voltage U _{ref are} taken.

The result, apart from the reference voltage U _ref to be tested, depends only on the values of the components within the oscillator and the Wien-Robinson bridge, which values can be set by a single calibration. The test is thus independent of external reference voltages.

U _ref

reference voltage

W

Wien Bridge

a

output the Vienna-Robinson-Bridge

b

output the Vienna-Robinson-Bridge

O

oscillator

P

phase detector

fail

signal

passport

signal

rn

resistors

cn

capacitors

f _x≈

frequency

Claims (2)

Method for self-testing a reference voltage in electronic components, characterized in that the reference voltage (U _ref ) is supplied to a voltage-dependent oscillator (O) whose output forms the input of a Wien-Robinson bridge (W), the output signal of which is in a phase detector (P ) is checked with respect to its phase shift relative to the entrance of the Wien-Robinson bridge (W) to the balance of the Wien-Robinson bridge (W), the balance of the Wien-Robinson bridge (W) being set to a frequency, which is generated in the voltage-dependent oscillator (O) at the _rated value (U _{ref, test} ) selected for the reference voltage (U _ref ) and, if the Wien-Robinson bridge (W) is matched, a pass signal (pass) non-existing adjustment of the Vienna-Robinson bridge (W) a fail signal (fail) is generated. Circuit arrangement for self-testing a reference voltage (U _ref ) in electronic components, characterized in that it comprises a voltage-dependent oscillator (O) whose output voltage is fed to a Wien-Robinson bridge (W) whose output is the input of a phase detector (P) forms, with the balance of the Wien-Robinson bridge (W) is set to a frequency (U _{ref, test)} in the oscillator (O) in which for the reference voltage (U _ref) chosen nominal value is generated and the output of the Phase detector (P) generates a fail signal (fail) and generates a pass signal (pass) when a threshold value is exceeded, if the threshold is not exceeded.